Anti-corrosion composition

ABSTRACT

The present invention provides an anti-corrosion composition which can be applied to various substrates. The composition comprises a glass matrix formed by crosslinking a mixture of an amine-functionalized silane and an alkoxy-functionalized siloxane, an epoxy and a compatabilizing agent for coupling the epoxy and the alkoxy-functionalized siloxane of the glass matrix.

RELATED APPLICATIONS

[0001] This application claims priority to U.S. Provisional Application No. 60/417,708; filed on Oct. 10, 2002, the disclosure of which is incorporated herein by reference in its entirety.

FIELD AND BACKGROUND OF THE INVENTION

[0002] The present invention relates to an anti-corrosion composition suitable for use on a variety of substrates. Of particular interest is the use of the composition as a coating for corrosive industrial environments such as smoke stacks, rail cars, hoppers, factory floors, pipe linings, engine rooms and the like.

[0003] Metal substrates and related parts in such industrial environments are subjected to a number of acids and bases due to the variety of compositions that pass through, contact, or are contained in the industrial environment. For example, a rail car may have a solvent such as a highly polar alcohol sitting in the rail car for months or even longer periods of time. Similarly, an acid such as sulphuric acid may be generated due to an industrial process and caused to exit a smokestack on a substantially constant basis. Often, the only way to avoid the corrosive nature of such acids or bases is to completely scrap the article after a period of use. Alternatively, use of the article can be discontinued so that a lengthy cleaning can occur. These alternatives are expensive and can lead to long down times caused by replacement or the discontinued use. It would be desirable to have an alternative that would allow the article to be used for a longer time. Thus, there is a need for an anti-corrosive coating that can withstand a wide variety of acid or base conditions, and can be simply and inexpensively applied to a substrate.

SUMMARY OF THE INVENTION

[0004] The anti-corrosion composition of the present invention includes a glass matrix formed by crosslinking a mixture of an amine-functionalized silane and an alkoxy-functionalized siloxane, an epoxy, and optionally and preferably a compatibilizing agent for coupling the epoxy and the alkoxy-functionalized siloxane of the glass matrix. The epoxy can further include a curing agent, preferably an amine. The amine-functionalized silane preferably is compatible with the amine curing agent. The composition, once crosslinked, is an epoxy-modified interpenetrating network of glass and epoxy. The present invention also provides a treated substrate for use in an industrial environment, and includes various metals such as steel, stainless steel, aluminium, magnesium and zinc.

DETAILED DESCRIPTION OF THE INVENTION

[0005] As discussed above, the anti-corrosion composition comprises a glass matrix formed by crosslinking a mixture of an amine-functionalized silane and an alkoxy-functionalized siloxane, an epoxy, and, optionally, a compatibilizing agent for coupling the epoxy and the alkoxy-functionalized siloxane of the glass matrix. The glass matrix is crosslinked using a titanium or tin catalyst. Suitable catalysts include, without limitation, titanium alkoxides such as titanium methoxide, titanium ethoxide, titanium isopropoxide, titanium propoxide, titanium butoxide, titanium diisopropoxide (bis 2,4-pentanedionate), titanium diisopropoxide bis(ethylacetoacetateo)titanium ethylhexoxide, and organic tin compounds such as dibutyl tin diacetate, dibutyltin dilaurate, dimethyl tin dineodecanoate, dioctyl dilauryl tin, and dibutyl butoxy chlorotin, as well as mixtures thereof. The glass matrix can be formed by using a Sol-Gel process such as described in U.S. Pat. No. 6,313,193, the disclosure of which is incorporated herein by reference in its entirety. Other methods of forming the matrix will be within the skill of one in the art. The glass matrix provides good adhesion to the surface being coated, as well as toughness, crack resistance, durability, abrasion resistance, heat resistance and stability in the particular environment.

[0006] The matrix formulation may also include fillers (e.g., fumed silica, mica, kaolin, bentonite, talc), zinc oxides, zinc phosphates, iron oxides, cellulose, pigments, corrosion inhibitors, UV light stabilizers, thixotropic agents, epoxy modifiers, polytetrafluoroethylene powder, ultra high molecular weight polyethylene powder, high, medium and low molecular weight polyethylene powder, or other additives, as will be readily apparent to those skilled in the art.

[0007] Suitable amino-functionalized silanes include 3-aminopropyltriethoxy silane, 3-aminopropyldimethylethoxy silane, 3-aminopropyl methyldiethoxy silane and 3-aminopropyltrimethoxy silane. Suitable alkoxy-functionalized siloxanes include polydiethoxysiloxane, tetraethoxysilane, tetramethoxysilane and polydimethoxy siloxane. Inasmuch as these compounds form silicates through a water condensation reaction, the inherent moisture of metal being treated can be used to facilitate the reaction without having to remove the moisture. Thus substrates such as stem pipes can be easily and inexpensively treated by using the moisture on the outside of the pipe to facilitate the crosslinking reaction.

[0008] Epoxy compounds are well known and are described in, for example, U.S. Pat. Nos. 2,467,171; 2,615,007; 2,716,123; 3,030,336; and 3,053,855 which are incorporated herein by reference in their entirety. Useful epoxy compounds include the polyglycidyl ethers of polyhydric polyols, such as ethylene glycol, triethylene glycol, 1,2-propyleneglycol, 1,5-pentanediol, 1,2,6-hexanetriol, glycerol and 2,2-bis(4-hydroxy cyclohexyl)propane; the polyglycidyl esters of aliphatic or aromatic polycarboxylic acids, such as oxalic acid, succinic acid, glutaric acid, terephthalic acid, 2,6-naphthalene dicarboxylic acid and dimerized linoleic acid; the polyglycidyl ethers of polyphenols, such as 2,2-bis(4-hydroxyphenyl)propane (commonly known as bis-phenol A), 1,1-bis(4-hydroxyphenyl)ethane, 1,1-bis(4-hydroxyphenyl)isobutane, 4,4′-dihydroxybenzophenone, 2,2-bis(4hydroxyphenyl)butane, bis(2-dihydroxynaphthyl)methane, phloroglucinol, bis(4hydroxyphenyl)sulfone, 1,5-dihydroxynaphthalene, and novolak resins; with the bifunctional epoxies such as polyglycidyl ethers of a polyphenol, polybisphenol A-epichlorohydrin glycidyl end-capped and polybisphenol F-epichlorodydrin glycidyl end-capped being currently preferred.

[0009] Generally the preferred epoxy compounds are resins having an epoxide equivalent weight of about 100 to 2000, preferably about 110 to 500. A presently preferred epoxy is EPON 862 available from Resolution Performance Products, Houston, Tex. Epoxy modifiers may be added to improve flexibility.

[0010] Suitable curing agents include Ancamide 220, a polyamide curing agent available from Air Products, Allentown, Pa.

[0011] Silanes capable of compatibilizing the epoxy and the alkoxy-functionalized siloxane include glycidyl-modified silanes such as 3-(glycidoxypropyl)trimethoxysilane, 3-(glycidoxypropyl)dimethylethoxysilane and 3-(glycidoxypropyl)methyldimethoxysilane. Benzyl alcohol can also be used to help compatibilize the epoxy and alkoxy-functionalized siloxane.

[0012] The matrix preferably comprising about 10 to 50 percent by weight of the glass matrix, about 5 to 50 percent by weight epoxy, 0 to 10 percent by weight compatibilizing agent and 5 to 20 percent by weight curing agent.

[0013] In operation, the anti-corrosion composition of the present invention can be applied by roll-coating, brush, spray coating, dipping and the like. As discussed above, it is preferred that the user mix the catalyst with the other components right before or substantially contemporaneously with application. The composition is preferably applied at a thickness of about 0.25 mm to 1.0 mm.

EXAMPLES

[0014] The following examples are provided to afford a better understanding of the present invention to those skilled in the art. It is to be understood that these examples are intended to be illustrative only and are not intended to limit the invention in any way.

Example 1

[0015] Component wt (%) Epon 862 epoxy resin 10.98 Ancamide 220 polyamide curing agent 10.98 (3-glycidoxypropyl)trimethoxysilane 14.00 3-aminopropyltriethoxysilane  6.98 polydiethoxysiloxane 12.16 titanium isopropoxide  5.75 benzyl alcohol  4.72 pigment  1.57 mica flakes 32.96

[0016] The composition is formulated such that the epoxy functionality on the 3-(glycidoxypropyl)-methoxysilane is at a 1:1 stoichiometric ratio with the amine functionality of the Ancamide 220. The epoxy functionality of the 862 resin is at a 1:1 stoichiometric ratio with the amine functionality of the aminopropyl triethoxysilane. The ethoxy groups on polydiethoxy siloxane are at a 1:1 stoichiometric ratio with the sum of the number of moles of aminopropyl triethoxysilane and the 3-(glycidoxyproply)trimethoxysilane.

[0017] Pencil hardness measurements of the coating after 7 days indicate that the coating has a hardness value of 6H. Samples were exposed to toluene, MEK, ethanol, paint thinner, 50% acetic acid and grill cleaner (e.g., potassium hydroxide, ethylene glycol monobutyl ether and monoethanolamine) for a period of 1 hour under a watch glass.

[0018] Pencil hardness measurements were then conducted on the areas of the sample which had been exposed to the chemical. For all cases, except the acids, there were no changes in the pencil hardness. Samples formulated with mica and exposed to the acids decreased in hardness to H or less. Samples formulated with glass and exposed to the acids only decreased in hardness to 5H.

Example 2

[0019] Component wt (%) Epon 862 (epoxy resin)  8.34 3-(glycidoxypropyl)trimethoxy silane 10.63 polydiethoxy siloxane  9.24 titanium isopropoxide  4.29 Heucophos ZPO (organo-zinc corrosion inhibitor)  8.20 Heucorin RZ (zinc salt corrosion inhibitor)  0.91 Custermica A325 (mica) 35.76 fumed silica TS-720 (thixotropic agent)  0.89 Kronos 2160 (titanium oxide)  5.97 Vulcan XC72R (carbon black)  0.12 Ancamide 220 (polyamide curing agent)  8.34 3-aminopropyltriethoxy silane  5.31 Hostavin N24 (UV light stabilizer)  2.00

[0020] The resulting coating displays good adhesion with conventional topcoats. It is more thermally resistant than conventional epoxy resins. Using ASTM G26 and continuous exposure to a xenon arc for 500 hours, no cracking or delamination occurs. With respect to fluid resistance, ASTM D5402 is used to test a variety of fluids. The coating is resistant to toluene, paint remover, ethanol, brake fluid, grill cleaner, mineral spirits, MEK and caustic acid.

Example 3

[0021] Component wt (%) Epon 862 (epoxy resin)  4.99 Heloxy 505 (epoxy modifier)  4.99 3-(glycidoxypropyl)methyldiethoxy silane 10.52 polydiethoxy siloxane  9.15 titanium isopropoxide  4.24 Heucophos ZPO (organo-zinc corrosion inhibitor)  8.11 Heucorin RZ (zinc salt corrosion inhibitor)  0.90 Custermica A325 (mica) 35.39 fumed silica TS-720 (thixotropic agent)  0.88 Kronos 2160 (titanium oxide)  5.91 Vulcan XC72R (carbon black)  0.11 Ancamide 220 (polyamide curing agent)  9.43 3-aminopropyltriethoxy silane  3.38 Hostavin N24 (UV light stabilizer)  2.00

[0022] In the specification and example, there have been disclosed typical preferred embodiments of the invention and, although specific terms are employed, they are used in a generic and descriptive sense only and not for purposes of limitation of the scope of the invention set forth in the following claims. 

That which is claimed is:
 1. An anti-corrosion composition comprising: (a) a glass matrix formed by crosslinking a mixture of an amine-functionalized silane and an alkoxy-functionalized siloxane; (b) an epoxy; and (c) a compatabilizing agent for coupling the epoxy and the alkoxy-functionalized siloxane of the glass matrix.
 2. The anti-corrosion composition according to claim 1, wherein the anti-corrosion composition further comprises a curing agent
 3. The anti-corrosion composition according to claim 1, wherein the compatibilizing agent is 3-(glycidoxypropyl)trimethoxysilane.
 4. The anti-corrosion composition according to claim 1, wherein the epoxy is bifunctional.
 5. The anti-corrosion composition according to claim 2, wherein the curing agent is an amine.
 6. The anti-corrosion composition according to claim 4, wherein the anti-corrosion composition further includes an aminosilane compatible with the amine curing agent.
 7. The anti-corrosion composition according to claim 1, wherein the alkoxy-functionalized siloxane is selected from the group consisting of polydiethoxysiloxane, polydimethoxysiloxane, tetramethoxy silane and tetraethoxy silane.
 8. The anti-corrosion composition according to claim 1, wherein the composition further comprises an additive.
 9. The anti-corrosion composition according to claim 7, wherein the additive is selected from the group consisting of fumed silica, mica, kaolin, bentonite, talc, zinc oxides, zinc phosphates, iron oxides, cellulose, pigments, polytetrafluoroethylene powder, ultra high molecular weight polyethylene powder, high, medium and low molecular weight polyethylene powder.
 10. The anti-corrosion composition according to claim 1, wherein the glass matrix is crosslinked using an organotitanate or tin catalyst.
 11. A method of treating a substrate to prevent corrosion, the method comprising: (a) applying to the substrate a composition comprising a glass matrix formed by crosslinking a mixture of an amine-functionalized silane and an alkoxy-functionalized siloxane, an epoxy, and a compatiblizing agent for coupling the epoxy and the alkoxy-functionalized siloxane of the glass matrix; (b) crosslinking the composition to provide an epoxy-modified network of glass and epoxy.
 12. The method of treating a substrate to prevent corrosion according to claim 11, wherein the compatibilizing agent is 3-(glycidoxypropyl)trimethoxysilane.
 13. The method of treating a substrate to prevent corrosion according to claim 11, wherein the anti-corrosion composition further includes an aminosilane compatible with the amine curing agent.
 14. The method of treating a substrate to prevent corrosion according to claim 11, wherein the composition further comprises an additive.
 15. The method of treating a substrate to prevent corrosion according to claim 11, wherein the additive is selected from the group consisting of filmed silica, mica, kaolin, bentonite, talc, zinc oxides, zinc phosphates, iron oxides, cellulose, pigments, polytetrafluoroethylene powder, ultra high molecular weight polyethylene powder, high, medium and low molecular weight polyethylene powder.
 16. The method of treating a substrate to prevent corrosion according to claim 11, wherein the glass matrix is crosslinked using an organotitanate or tin catalyst.
 17. A substrate having applied thereto an anti-corrosion composition comprising a glass matrix formed by crosslinking a mixture of an amine-functionalized silane and an alkoxy-functionalized siloxane, an epoxy, and a compatabilizing agent for coupling the epoxy and the alkoxy-functionalized siloxane of the glass matrix.
 18. The substrate according to claim 17 wherein the substrate is a metal.
 19. The substrate according to claim 17, wherein the anti-corrosion composition further comprises a curing agent
 20. The substrate according to claim 17, wherein the compatibilizing agent is 3-(glycidoxypropyl)trimethoxysilane.
 21. The substrate according to claim 17, wherein the epoxy is bifunctional.
 22. The substrate according to claim 19, wherein the curing agent is an amine.
 23. The substrate according to claim 17, wherein the anti-corrosion composition further includes an aminosilane compatible with the amine curing agent.
 24. The substrate according to claim 17, wherein the alkoxy-functionalized siloxane is selected from the group consisting of polydiethoxysiloxane, polydimethoxysiloxane, tetramethoxy silane and tetraethoxy silane.
 25. The substrate according to claim 17, wherein the composition further comprises an additive.
 26. The substrate according to claim 25, wherein the additive is selected from the group consisting of fumed silica, mica, kaolin, bentonite, talc, zinc oxides, zinc phosphates, iron oxides, cellulose, pigments, polytetrafluoroethylene powder, ultra high molecular weight polyethylene powder, high, medium and low molecular weight polyethylene powder.
 27. The substrate according to claim 17, wherein the glass matrix is crosslinked using an organotitanate or tin catalyst. 